[Backend Tester] Run Core ML tests in nightly CI (pytorch#13446)

Add nightly CI jobs to run the Core ML test backend test flows.

Author: GregoryComer

.ci/scripts/test_backend_macos.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+set -eux
+
+SUITE=$1
+FLOW=$2
+ARTIFACT_DIR=$3
+
+echo "Running backend test job for suite $SUITE, flow $FLOW."
+echo "Saving job artifacts to $ARTIFACT_DIR."
+
+${CONDA_RUN} --no-capture-output pip install awscli==1.37.21
+
+bash .ci/scripts/setup-conda.sh
+eval "$(conda shell.bash hook)"
+
+PYTHON_EXECUTABLE=python
+${CONDA_RUN} --no-capture-output .ci/scripts/setup-macos.sh --build-tool cmake --build-mode Release
+
+${CONDA_RUN} --no-capture-output python -m executorch.backends.test.suite.runner $SUITE --flow $FLOW --report "$ARTIFACT_DIR/test_results.csv"

.github/workflows/nightly.yml

@@ -58,3 +58,30 @@ jobs:
         EXIT_CODE=0
         .ci/scripts/test_backend_linux.sh "${{ matrix.suite }}" "${{ matrix.flow }}" "${RUNNER_ARTIFACT_DIR}" || EXIT_CODE=$?
         echo "Test run complete with exit code $EXIT_CODE."
+
+  backend-test-macos:
+    uses: pytorch/test-infra/.github/workflows/macos_job.yml@main
+    permissions:
+      id-token: write
+      contents: read
+    strategy:
+      fail-fast: false
+      matrix:
+        flow: [coreml, coreml_static_int8]
+        suite: [models, operators]
+    with:
+      ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
+      runner: macos-m1-stable
+      python-version: 3.12
+      submodules: recursive
+      timeout: 120
+      upload-artifact: test-report-${{ matrix.flow }}-${{ matrix.suite }}
+      script: |
+        set -eux
+
+        # This is needed to get the prebuilt PyTorch wheel from S3
+        ${CONDA_RUN} --no-capture-output pip install awscli==1.37.21
+
+        EXIT_CODE=0
+        .ci/scripts/test_backend_macos.sh "${{ matrix.suite }}" "${{ matrix.flow }}" "${RUNNER_ARTIFACT_DIR}" || EXIT_CODE=$?
+        echo "Test run complete with exit code $EXIT_CODE."